The present invention relates to an electrical machine with a vertical shaft and a fan secured on the rotor shaft below the rotor plate packet, centered on a hub and removable from the hub.
In known self-ventilated vertical electrical machines, a fan for circulating cooling air is customarily arranged below the electrically active parts of the rotor in such a way that the cooling air can be drawn in from above the machine with as few impurities as possible and be blown out in a bottom region of the machine. Further, it must be possible to lift the rotor upward out of the machine casing for maintenance purposes. This, however, requires first unscrewing the fan, which generally has a greater diameter than the rotor, and depositing it in the casing.
Usually, axially extending screws are used to fasten the fan on the hub. When reinstalling the rotor after maintenance, the fan must then again be centered on the hub, and the attachment holes in the fan and in the hub must register exactly in circumferential direction to be able to introduce the axial screws. This may present difficulties for machines of relatively great power because vision onto the location of the fan attachment is obstructed by the casing. Besides, the weight of the rotor of the electrical machine, as well as that of the fan, hinders the assembly operation.